The present invention relates generally to imaging systems, such as radiographic systems, and more particularly, to multi-tile detector assemblies used in such systems. Even more particularly, the present invention relates to a system and method for assembling detector tiles in a manner that minimizes or prevents visible artifacts associated with the tiling.
Medical diagnostic and imaging systems are ubiquitous in modern health care facilities. Currently, a number of modalities exist for medical diagnostic and imaging systems. These include computed tomography (CT) systems, x-ray systems (including both conventional and digital/digitized imaging systems), magnetic resonance (MR) systems, positron emission tomography (PET) systems, ultrasound systems, nuclear medicine systems, and so forth. Such systems provide invaluable tools for identifying, diagnosing and treating physical conditions and greatly reduce the need for surgical diagnostic intervention. In many instances, these modalities complement one another and offer the physician a range of techniques for imaging particular types of tissue, organs, physiological systems, and so forth.
Medical imaging systems often generate images by radiating a non-intrusive source into the patient and by reconstructing an image from the portion passing through the patient and impacting an imaging detector. In many imaging systems, the imaging detector may comprise a detector surface comprising a plurality of the detector tiles. For example, x-ray, computed tomography, positron emission tomography, nuclear, and gamma ray imaging detectors often use an ionizing photon detector material, such as Cadmium Zinc Telluride (CZT), Cadmium Telluride (CdTe), and various other crystalline semiconductor materials, which have size limitations due to a variety of production factors. For example, imaging detectors using the CZT material generally require multiple tiles, because CZT crystals can only be grown in relatively small sizes due to yield problems with current technology.
Accordingly, a plurality of CZT detector tiles are connected to a substrate, such as a silicon wafer or die, in a tiled arrangement to provide the desired size for the imaging detector. Unfortunately, the tiling process tends to create gaps that create visible artifacts in the reconstructed image. The assembly of detector tiles is also complicated by the need to connect the detector tiles electronically to their respective die, which then must be connected to the rest of the image receptor. Due to the nature of direct conversion detection of ionizing photons, an electrical connection is necessary between each detector tile and its respective die at each detection element and between each adjacent die (e.g., along at least one edge of each adjacent die). Moreover, an electrical connection is necessary between the metallized layers of each adjacent detector tile to provide the same voltage potential during imaging. The different coefficients of thermal expansion of the detector and wafer materials also complicate the foregoing electrical connections, because the temperature restraints for assembly further limit the assembly size of the detector tiles.
Accordingly, a technique is needed for assembling a plurality of detector tiles in a manner that minimizes or prevents visible artifacts associated with the tiling. In particular, a technique is needed for reducing gaps between adjacent detector tiles.